Start by flattening the chicken using a meat pounder or the bottom of a frying pan. Then, gently flatten the chicken to ¼ inch.
Season with salt and pepper. Set aside.
Combine the breadcrumbs with the chopped nuts.
Heat a saute pan over medium heat, add the butter and saute the mushrooms until soft. And the mint leaves and remove from heat.
Layer each chicken breast with spinach, Swiss cheese, prosciutto, and sauteed mushrooms, then fold the chicken in half and seal the edges by pressing with your fingers. You may need toothpicks to help secure the chicken.
Dip each chicken breast into the flour batter, and be sure to let the excess batter drip off. Cover both sides with breadcrumbs and reserve.
Reheat the saute pan over low heat, add the butter and oil and wait until it gets hot but not smoking. Saute the chicken breasts until golden brown on each side and fully cooked. To serve, place each chicken breast into the center of the plate, spoon some sauce over the chicken breasts or on the side and add your side vegetables.